The present invention relates to electrical cord connectors of the type including means for securely clamping a multi-conductor cable at a position closely adjacent the connections of the individual conductors to the terminals of the connector.
Both male and female type connectors are commonly provided on the end of electrical cords and cables in such manner that twisting, tension, or other forces applied to the cable are not transmitted to the connections of the conductors with the terminals within the connector. That is, means are provided for firmly clamping the insulated cord or cable at a position within or closely adjacent the connector housing, such means being commonly termed strain-relief clamps or bushings. The strain-relief means of the prior art, as well as of the present invention, may be employed not only in male and female connectors, but in other wiring devices, such as cube taps, cord-mounted switches, electrical plugs and caps, and electrical connections in a panel or wiring box or appliance housing.
Among the types of structures used in strain-relief cable clamping are those embodied in a cylindrical housing with an opening through the center of one end for passage of the cord. At least two portions of the housing are movable relative to one another to permit insertion of the cord and clamping thereof between the relatively movable portions. The individual conductors are connected in electrically communicating relation with terminals of the wiring device which is inside, or otherwise fixed with respect to the housing.
In one popular form of such connector, a cylindrical housing is divided into two separate sections along both radial and axial lines. That is, one of the two pieces is formed as a full cylinder over a portion of its length, and in semi-cylindrical form over the remaining portion. The other piece is semi-cylindrical and mates with the semi-cylindrical portion of the first piece to complete the generally cylindrical configuration of the assembled housing. The two pieces are held in assembled relation by two screws passing, perpendicularly to and on opposite sides of the central axis of the housing, through openings in the semi-cylindrical piece into threaded or self-tapping openings in the semi-cylindrical portion of the other piece. The cable is positioned and clamped firmly between the two semi-cylindrical pieces.
One disadvantage of this configuration is that the smaller of the two housing pieces, i.e., the semi-cylindrical piece, is fully exposed on the exterior of the housing and, under some conditions, may tend to become loose or dislodged. This is sometimes exacerbated by the fact that the connector is expected to accommodate cables of different diameters and, when larger cables are used, the semi-cylindrical piece may protrude outwardly from the axially adjoining, cylindrical surface of the other piece. A second drawback is that there is no dielectric barrier between the metallic screws which hold the two housing pieces together and the conductors of the cable attached thereto, other than the insulation on the conductors, a portion of which is stripped away to permit connection of the conductors to the terminals within the connector. A third drawback is that when the attached cable is flexed axially, sufficient force can be applied to the clamping piece to cause it to move and create gaps and access to the terminal conductor connection.
It is a principal object of the present invention to provide an electrical connector having terminals for connection to individual conductors of a cylindrical cable with strain-relief cable clamping means embodied in a two-part housing of novel and improved design.
A further object is to provide a strain-relief cable connector including a two-part housing wherein a semi-cylindrical portion of the cable clamp is not exposed on the exterior of the housing.
Another object is to provide an electrical connector wherein a cylindrical cable is clamped between two, screw-connected pieces of housing incorporating means forming a dielectric barrier between the screw fasteners and the individual conductors of the cable.
Other objects will in part be obvious and will in part appear hereinafter.